On Transverse-Momentum Dependent Light-Cone Wave Functions of Light Mesons

Transverse-momentum dependent (TMD) light-cone wave functions of a light meson are important ingredients in the TMD QCD factorization of exclusive processes. This factorization allows one conveniently resum Sudakov logarithms appearing in collinear factorization. The TMD light-cone wave functions are not simply related to the standard light-cone wave functions in collinear factorization by integrating them over the transverse momentum. We explore relations between TMD light-cone wave functions and those in the collinear factorization. Two factorized relations can be found. One is helpful for constructing models for TMD light-cone wave functions, and the other can be used for resummation. These relations will be useful to establish a link between two types of factorization.Comment: add more discussions and reference

Intrinsic Charm in B-Meson Decays

Light cone hadron wave functions support Fock states of arbitrarily high particle number: their heavy quark content arises naturally through QCD interactions. We discuss what role c\bar c pairs, intrinsic to a hadron's structure, can play in B-meson decays. The effects can be prominent in hadronic decays for which the tree-level contributions are Cabibbo-suppressed, as in B\to \pi K decay, and they mimic ``charming penguin'' contributions.Comment: 7 pages, 4 figs, invited talk at the 5th Int'l Conf. on Hyperons, Charm and Beauty Hadrons (BEACH 2002), Univ. of British Columbia, Vancouver, June 25-29,2002, to appear in the proceeding

Intrinsic Charm Contribution to Double Quarkonium Hadroproduction

Double $J/\psi$ production has been observed by the NA3 collaboration in $\pi N$ and $p N$ collisions with a cross section of the order of 20-30 pb. The $\psi \psi$ pairs measured in $\pi^-$ nucleus interactions at 150 and 280 GeV$/c$ are observed to carry an anomalously large fraction of the projectile momentum in the laboratory frame, $x_{\psi \psi} \geq 0.6$ at 150 GeV$/c$ and $\geq 0.4$ at 280 GeV$/c$. We postulate that these forward $\psi \psi$ pairs are created by the materialization of Fock states in the projectile containing two pairs of intrinsic $c \overline c$ quarks. We calculate the overlap of the charmonium states with the $|\overline u d c \overline c c \overline c \rangle$ Fock state as described by the intrinsic charm model and find that the $\pi^- N \rightarrow \psi \psi$ longitudinal momentum and invariant mass distributions are both well reproduced. We also discuss double $J/\psi$ production in $pN$ interactions and the implications for other heavy quarkonium production channels in QCD.Comment: Revtex, APS style, 7 pages, 3 figures in uuencoded fil

Nonlocal PMD compensation in the transmission of non-stationary streams of polarization entangled photons

We study the feasibility of nonlocally compensating for polarization mode dispersion (PMD), when polarization entangled photons are distributed in fiber-optic channels.We quantify the effectiveness of nonlocal compensation while taking into account the possibility that entanglement is generated through the use of a pulsed optical pump signal

The systematic study of B→πB\to \pi form factors in pQCD approach and its reliability

The study of exclusive B decays in perturbative QCD are complicated by the endpoint problem. In order to perform the perturbative calculation, the Sudakov effects are introduced to regulate the endpoint singularity. We provide a systematic analysis with leading and next-to-leading twist corrections for $B\to\pi$ form factors in pQCD approach. The intrinsic transverse momentum dependence of hadronic wave function and threshold resummation effects are included in pQCD approach. There are two leading twist B meson distribution amplitudes (or generally wave functions) in general. The QCD equations of motion provide important constraints on B meson wave functions. The reliability of pQCD approach in \bpi form factors is discussed. 70% of the result comes from the region $\alpha_s(t)/\pi<0.2$ and 38% comes from the region where the momentum transfer t\geq 1\GeV. The conceptual problems of pQCD approach are discussed in brief. Our conclusion is that pQCD approach in the present form cannot provide a precise prediction for \bpi transition form factors.Comment: 30 pages, latex, some typos corrected, to appear in Nucl. Phys.

Study of electromagnetic decay of J/ψJ/\psi and ψ′\psi^\prime to vector and pseudoscalar

The electromagnetic decay contributions to $J/\psi(\psi^\prime)\to VP$, where $V$ and $P$ stand for vector and pseudoscalar meson, respectively, are investigated in a vector meson dominance (VMD) model. We show that $J/\psi (\psi^\prime)\to \gamma^*\to VP$ can be constrained well with the available experimental information. We find that this process has significant contributions in $\psi^\prime\to VP$ and may play a key role in understanding the deviations from the so-called "12% rule" for the branching ratio fractions between $\psi^\prime\to VP$ and $J/\psi\to VP$. We also address that the "12% rule" becomes very empirical in exclusive hadronic decay channels.Comment: Revtex, 10 pages, 1 eps figure; further discussions about the helicity conservation rule and exp. constraints are included; version to appear in Phys. Lett.

Two-parton twist-3 factorization in perturbative QCD

We prove collinear factorization theorem for the process $\pi\gamma^*\to\pi$ at the twist-3 level in the covariant gauge by means of the Ward identity, concentrating on the two-parton case. It is shown that soft divergences cancel and collinear divergences are grouped into the pseudo-scalar and pseudo-tensor two-parton twist-3 pion distribution amplitudes. The delicate summation of a complete set of diagrams for achieving factorization in momentum, spin, and color spaces is emphasized. The proof is then extended to the exclusive semileptonic decay $B\to\pi l\bar\nu$, assuming the hard scale to be of $O(\sqrt{\bar\Lambda M_B})$, where $\bar\Lambda$ is a hadronic scale and $M_B$ the $B$ meson mass. We explain the distinction between the factorization of collinear divergences for a pion distribution amplitude and of soft divergences for a $B$ meson distribution amplitude. The gauge invariance and universality of the two-parton twist-3 pion distribution amplitudes are confirmed. The proof presented here can accommodate the leading twist-2 case. We then compare our proof with that performed in the framework of soft-collinear effective theory.Comment: 43 pages, 7 figures, many parts rewritten and updated reference

QCD Mechanisms for Double Quarkonium and Open Heavy Meson Hadroproduction

Double $J/\psi$ production on the order of 20-30 pb has been observed by the NA3 collaboration. These $\psi \psi$ pairs, measured in $\pi^- N$ interactions at 150 and 280 GeV$/c$ and in $pN$ interactions at 400 GeV$/c$, carry a large fraction of the projectile momentum, $x_{\psi \psi} \geq 0.6$ for the 150 GeV$/c$ beam and $\geq 0.4$ at 280 GeV$/c$. We examine several sources of $\psi \psi$ pair production within QCD, including ${\cal O}(\alpha_s^4)$ $\psi \psi$ production, leading-twist $b \overline b$ production and decay, and the materialization of heavy-quark Fock states in the projectile. We estimate the production cross section and the single and double $J/\psi$ momentum and mass distributions for each, comparing the results with the NA3 data, and predict $\psi \psi$ production in $pN$ interactions at 800 GeV$/c$, accessible to current fixed-target experiments. We also discuss the observable implications of open heavy meson pair production from the intrinsic heavy quark Fock states.Comment: Revtex, APS style, 16 pages, 15 figures available as uuencoded postscript files (or ps files) from the Autho

Hamiltonian light-front field theory within an AdS/QCD basis

Non-perturbative Hamiltonian light-front quantum field theory presents opportunities and challenges that bridge particle physics and nuclear physics. Fundamental theories, such as Quantum Chromodynmamics (QCD) and Quantum Electrodynamics (QED) offer the promise of great predictive power spanning phenomena on all scales from the microscopic to cosmic scales, but new tools that do not rely exclusively on perturbation theory are required to make connection from one scale to the next. We outline recent theoretical and computational progress to build these bridges and provide illustrative results for nuclear structure and quantum field theory. As our framework we choose light-front gauge and a basis function representation with two-dimensional harmonic oscillator basis for transverse modes that corresponds with eigensolutions of the soft-wall AdS/QCD model obtained from light-front holography.Comment: To appear in the proceedings of Light-Cone 2009: Relativistic Hadronic and Particle Physics, July 8-13, 2009, Sao Jose dos Campos, Brazi

Sudakov effects in BBNS approach

The end-point singularity is an unsolved problem in BBNS approach. Incorporating the partonic transverse momentum and the Sudakov form factor, this problem can be solved model-independently. We discuss the Sudakov effects in BBNS approach. The BBNS approach is compared with the modified PQCD approach. The main idea of Sudakov form factor is briefly discussed. Our conclusion is that the twist-3 contribution for the hard spectator scattering is numerically not important in $B\to \pi\pi$ decays, compared with the twist-2 contribution.Comment: 16 pages, Latex, two figures, some typos correcte